Number of Senior Citizens — LeetCode 2678 Python Solution

The problem

You are given a 0-indexed array of strings details. Each element of details provides information about a given passenger compressed into a string of length 15.

Example

Input

details = ["7868190130M7522","5303914400F9211","9273338290F4010"]

Output

2

Explanation

The passengers at indices 0, 1, and 2 have ages 75, 92, and 40. Thus, there are 2 people who are over 60 years old.

Python solution

class Solution:
    def countSeniors(self, details: List[str]) -> int:
        return sum(int(x[11:13]) > 60 for x in details)

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 2678. Number of Senior Citizens is filed here because the reference solution below belongs to the algorithm family this hub collects, even though its LeetCode tags point elsewhere.

The hash map guide has the Python template for the pattern and the 709 LeetCode problems that use it.

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